US9429682B2 - Method for preparing acrylic copolymer resin for optical film and method for fabricating optical film using the same - Google Patents
Method for preparing acrylic copolymer resin for optical film and method for fabricating optical film using the same Download PDFInfo
- Publication number
- US9429682B2 US9429682B2 US14/006,267 US201214006267A US9429682B2 US 9429682 B2 US9429682 B2 US 9429682B2 US 201214006267 A US201214006267 A US 201214006267A US 9429682 B2 US9429682 B2 US 9429682B2
- Authority
- US
- United States
- Prior art keywords
- weight parts
- acrylic
- meth
- monomer
- acrylic copolymer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active, expires
Links
- 229920005989 resin Polymers 0.000 title claims abstract description 93
- 239000011347 resin Substances 0.000 title claims abstract description 93
- 238000000034 method Methods 0.000 title claims abstract description 58
- 229920006243 acrylic copolymer Polymers 0.000 title claims abstract description 52
- 239000012788 optical film Substances 0.000 title claims abstract description 25
- 239000000178 monomer Substances 0.000 claims abstract description 72
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 claims abstract description 52
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims abstract description 30
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 26
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 claims abstract description 23
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 claims abstract description 22
- VANNPISTIUFMLH-UHFFFAOYSA-N glutaric anhydride Chemical group O=C1CCCC(=O)O1 VANNPISTIUFMLH-UHFFFAOYSA-N 0.000 claims abstract description 22
- 238000010557 suspension polymerization reaction Methods 0.000 claims abstract description 13
- 238000006116 polymerization reaction Methods 0.000 claims description 37
- 238000001125 extrusion Methods 0.000 claims description 29
- AOJOEFVRHOZDFN-UHFFFAOYSA-N benzyl 2-methylprop-2-enoate Chemical compound CC(=C)C(=O)OCC1=CC=CC=C1 AOJOEFVRHOZDFN-UHFFFAOYSA-N 0.000 claims description 28
- 238000006243 chemical reaction Methods 0.000 claims description 21
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical group COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 claims description 19
- 125000004432 carbon atom Chemical group C* 0.000 claims description 12
- 230000001965 increasing effect Effects 0.000 claims description 11
- 238000007669 thermal treatment Methods 0.000 claims description 9
- 230000009477 glass transition Effects 0.000 claims description 8
- 238000002360 preparation method Methods 0.000 claims description 7
- 238000002834 transmittance Methods 0.000 claims description 7
- BAPJBEWLBFYGME-UHFFFAOYSA-N Methyl acrylate Chemical group COC(=O)C=C BAPJBEWLBFYGME-UHFFFAOYSA-N 0.000 claims description 6
- -1 methylacryl Chemical group 0.000 claims description 5
- BQMWZHUIGYNOAL-UHFFFAOYSA-N 1-phenylethyl 2-methylprop-2-enoate Chemical compound CC(=C)C(=O)OC(C)C1=CC=CC=C1 BQMWZHUIGYNOAL-UHFFFAOYSA-N 0.000 claims description 3
- FEUFEGJTJIHPOF-UHFFFAOYSA-N 2-butyl acrylic acid Chemical compound CCCCC(=C)C(O)=O FEUFEGJTJIHPOF-UHFFFAOYSA-N 0.000 claims description 3
- WROUWQQRXUBECT-UHFFFAOYSA-N 2-ethylacrylic acid Chemical compound CCC(=C)C(O)=O WROUWQQRXUBECT-UHFFFAOYSA-N 0.000 claims description 3
- FYZUENZXIZCLAZ-UHFFFAOYSA-N 2-methylhept-2-enoic acid Chemical compound CCCCC=C(C)C(O)=O FYZUENZXIZCLAZ-UHFFFAOYSA-N 0.000 claims description 3
- JJYWRQLLQAKNAD-UHFFFAOYSA-N 2-methylpent-2-enoic acid Chemical compound CCC=C(C)C(O)=O JJYWRQLLQAKNAD-UHFFFAOYSA-N 0.000 claims description 3
- CEXQWAAGPPNOQF-UHFFFAOYSA-N 2-phenoxyethyl 2-methylprop-2-enoate Chemical compound CC(=C)C(=O)OCCOC1=CC=CC=C1 CEXQWAAGPPNOQF-UHFFFAOYSA-N 0.000 claims description 3
- RZVINYQDSSQUKO-UHFFFAOYSA-N 2-phenoxyethyl prop-2-enoate Chemical compound C=CC(=O)OCCOC1=CC=CC=C1 RZVINYQDSSQUKO-UHFFFAOYSA-N 0.000 claims description 3
- ILZXXGLGJZQLTR-UHFFFAOYSA-N 2-phenylethyl 2-methylprop-2-enoate Chemical compound CC(=C)C(=O)OCCC1=CC=CC=C1 ILZXXGLGJZQLTR-UHFFFAOYSA-N 0.000 claims description 3
- RXXZODOCQIRRQA-UHFFFAOYSA-N 3-phenylpropyl 2-methylprop-2-enoate Chemical compound CC(=C)C(=O)OCCCC1=CC=CC=C1 RXXZODOCQIRRQA-UHFFFAOYSA-N 0.000 claims description 3
- PKBZUGSITIBLFK-UHFFFAOYSA-N 3-phenylpropyl prop-2-enoate Chemical compound C=CC(=O)OCCCC1=CC=CC=C1 PKBZUGSITIBLFK-UHFFFAOYSA-N 0.000 claims description 3
- UIERETOOQGIECD-UHFFFAOYSA-N Angelic acid Natural products CC=C(C)C(O)=O UIERETOOQGIECD-UHFFFAOYSA-N 0.000 claims description 3
- JIGUQPWFLRLWPJ-UHFFFAOYSA-N Ethyl acrylate Chemical compound CCOC(=O)C=C JIGUQPWFLRLWPJ-UHFFFAOYSA-N 0.000 claims description 3
- 239000002253 acid Substances 0.000 claims description 3
- OUGJKAQEYOUGKG-UHFFFAOYSA-N ethyl 2-methylidenebutanoate Chemical compound CCOC(=O)C(=C)CC OUGJKAQEYOUGKG-UHFFFAOYSA-N 0.000 claims description 3
- SUPCQIBBMFXVTL-UHFFFAOYSA-N ethyl 2-methylprop-2-enoate Chemical compound CCOC(=O)C(C)=C SUPCQIBBMFXVTL-UHFFFAOYSA-N 0.000 claims description 3
- PNJWIWWMYCMZRO-UHFFFAOYSA-N pent‐4‐en‐2‐one Natural products CC(=O)CC=C PNJWIWWMYCMZRO-UHFFFAOYSA-N 0.000 claims description 3
- UIERETOOQGIECD-ONEGZZNKSA-N tiglic acid Chemical compound C\C=C(/C)C(O)=O UIERETOOQGIECD-ONEGZZNKSA-N 0.000 claims description 3
- 229920001577 copolymer Polymers 0.000 abstract description 18
- 230000015572 biosynthetic process Effects 0.000 abstract description 3
- 230000001939 inductive effect Effects 0.000 abstract description 2
- 239000010408 film Substances 0.000 description 69
- 230000000704 physical effect Effects 0.000 description 34
- 230000000052 comparative effect Effects 0.000 description 25
- 239000000203 mixture Substances 0.000 description 20
- 230000001681 protective effect Effects 0.000 description 12
- 230000010287 polarization Effects 0.000 description 10
- 230000003287 optical effect Effects 0.000 description 7
- 229920006026 co-polymeric resin Polymers 0.000 description 6
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 5
- 239000004973 liquid crystal related substance Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000004372 Polyvinyl alcohol Substances 0.000 description 4
- 239000003999 initiator Substances 0.000 description 4
- 235000019422 polyvinyl alcohol Nutrition 0.000 description 4
- 229920002451 polyvinyl alcohol Polymers 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000008188 pellet Substances 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 239000004925 Acrylic resin Substances 0.000 description 2
- 229920000178 Acrylic resin Polymers 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 125000003710 aryl alkyl group Chemical group 0.000 description 2
- 125000005160 aryl oxy alkyl group Chemical group 0.000 description 2
- 125000004104 aryloxy group Chemical group 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 210000002858 crystal cell Anatomy 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 238000000113 differential scanning calorimetry Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005227 gel permeation chromatography Methods 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000010558 suspension polymerization method Methods 0.000 description 2
- 238000001644 13C nuclear magnetic resonance spectroscopy Methods 0.000 description 1
- YAJYJWXEWKRTPO-UHFFFAOYSA-N 2,3,3,4,4,5-hexamethylhexane-2-thiol Chemical compound CC(C)C(C)(C)C(C)(C)C(C)(C)S YAJYJWXEWKRTPO-UHFFFAOYSA-N 0.000 description 1
- NFWPZNNZUCPLAX-UHFFFAOYSA-N 4-methoxy-3-methylaniline Chemical compound COC1=CC=C(N)C=C1C NFWPZNNZUCPLAX-UHFFFAOYSA-N 0.000 description 1
- 229920002284 Cellulose triacetate Polymers 0.000 description 1
- NNLVGZFZQQXQNW-ADJNRHBOSA-N [(2r,3r,4s,5r,6s)-4,5-diacetyloxy-3-[(2s,3r,4s,5r,6r)-3,4,5-triacetyloxy-6-(acetyloxymethyl)oxan-2-yl]oxy-6-[(2r,3r,4s,5r,6s)-4,5,6-triacetyloxy-2-(acetyloxymethyl)oxan-3-yl]oxyoxan-2-yl]methyl acetate Chemical compound O([C@@H]1O[C@@H]([C@H]([C@H](OC(C)=O)[C@H]1OC(C)=O)O[C@H]1[C@@H]([C@@H](OC(C)=O)[C@H](OC(C)=O)[C@@H](COC(C)=O)O1)OC(C)=O)COC(=O)C)[C@@H]1[C@@H](COC(C)=O)O[C@@H](OC(C)=O)[C@H](OC(C)=O)[C@H]1OC(C)=O NNLVGZFZQQXQNW-ADJNRHBOSA-N 0.000 description 1
- 150000001252 acrylic acid derivatives Chemical group 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 125000005250 alkyl acrylate group Chemical group 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 229920001400 block copolymer Polymers 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000011548 physical evaluation Methods 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 229920005604 random copolymer Polymers 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000000452 restraining effect Effects 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/10—Esters
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D7/00—Producing flat articles, e.g. films or sheets
- B29D7/01—Films or sheets
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/12—Polymerisation in non-solvents
- C08F2/16—Aqueous medium
- C08F2/18—Suspension polymerisation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/10—Esters
- C08F220/12—Esters of monohydric alcohols or phenols
- C08F220/14—Methyl esters, e.g. methyl (meth)acrylate
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/04—Homopolymers or copolymers of esters
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/04—Homopolymers or copolymers of esters
- C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/04—Homopolymers or copolymers of esters
- C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
- C08L33/08—Homopolymers or copolymers of acrylic acid esters
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/04—Homopolymers or copolymers of esters
- C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
- C08L33/10—Homopolymers or copolymers of methacrylic acid esters
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/04—Acids; Metal salts or ammonium salts thereof
- C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
-
- C08F2220/185—
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
Definitions
- the present invention relates to a method for preparing a resin for an optical film and, more particularly, to a method for fabricating an acrylic copolymer resin having excellent thermal stability.
- Advanced level requirements are required for a polymer material used for such displays.
- LCDs as LCDs are becoming thinner, lighter, and larger in terms of screen area, obtaining a wide viewing angle and a high contrast ratio, suppressing of a change in an image color according to a viewing angle, and making a screen display uniform have become particularly significant issues.
- various polymer films are used for a polarization film, a polarizer protective film, a retardation film, a plastic substrate, a light guide plate, and the like, and various modes of LCD devices using twisted nematic (TN), super-twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS) liquid crystal cells, and the like, as liquid crystal have been developed.
- These liquid crystal cells have a unique liquid crystal arrangement, respectively having a unique optical anisotropy, and, in order to compensate for the optical anisotropy, films obtained by stretching various types of polymers and providing retardation function thereto have been proposed.
- a polarization plate generally has a structure in which a triacetyl cellulose film (TAC) film is laminated on a polarizer as a protective film, using a water-based adhesive made of a polyvinylalcohol-based aqueous solution.
- TAC triacetyl cellulose film
- the degree of polarization may be degraded, the polarizer and the protective film may be separated, and optical characteristics may be degraded, such that the polarization plate is variably restricted in terms of the purpose thereof.
- the TAC film has an in-plane retardation value (R in ) and a thickness retardation value (R th ) which are severely changed according to changes in ambient temperature and moisture in the surrounding environment, and, in particular, a retardation value with respect to incident light in a tilt direction is greatly varied.
- R in in-plane retardation value
- R th thickness retardation value
- the TAC film has a great dimensional variation according to changes in ambient temperature and moisture environments and a relatively high photoelastic coefficient value.
- retardation characteristics may be changed locally to thereby degrade image quality.
- An acrylic resin has been well known as a material for complementing the various shortcomings of the TAC film.
- the acrylic resin does not have sufficient heat resistance characteristics, and creates a retardation in in-plane and thickness directions after being stretched, and therefore is not appropriate to be applied as a protective film.
- An aspect of the present invention provides a method for preparing an acrylic copolymer resin having excellent thermal stability, transparency, and optical physical properties.
- a method for preparing an acrylic copolymer resin for an optical film including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare an acrylic copolymer; and thermally treating the copolymer at a temperature ranging from 240° C. to 300° C.
- the suspension-polymerizing may include: a first polymerization operation of performing suspension polymerization at an initial reaction temperature ranging from 60° C. to 90° C. for two to three hours; and a second polymerization operation of increasing the temperature by 5° C. to 20° C., based on the temperature of the first polymerization operation, and additionally performing polymerization for one to two hours.
- the second polymerization operation may be performed at a temperature ranging from 80° C. to 100° C.
- the acrylic monomer containing a benzene ring may be selected from the group consisting of benzyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, 2-phenylethyl methacrylate, 3-phenylpropyl methacrylate, 3-phenylpropyl acrylate, and 2-phenoxyethyl acrylate.
- the alkyl group of the alkyl(meth)acrylate monomer may have 1 to 10 carbon atoms.
- the alkyl(meth)acrylate monomer may be selected from the group consisting of methylacrylate, ethylacrylate, methylmethacrylate, ethylmethacrylate, methylethacryate, and ethylethacrylate.
- the (meth)acrylic acid monomer may be selected from the group consisting of acrylic acid, methacrylic acid, methylacryl acid, methylmethacrylic acid, ethylacrylic acid, ethylmethacrylic acid, butylacrylic acid, and butylmethacrylic acid.
- the acrylic copolymer resin for an optical film obtained by the preparation method may include glutaric anhydride.
- the acrylic copolymer resin for an optical film obtained through the preparation method may include 3 to 15 weight parts of an acrylic unit containing a benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate unit, 0 to 4 weight parts of a (meth)acrylic acid unit, and 5 to 16 weight parts of a glutaric anhydride unit, over 100 weight parts of the acrylic copolymer resin.
- a glass transition temperature of the acrylic copolymer resin may be 120° C. or higher.
- Haze of the acrylic copolymer resin may range from 0.1 to 1%, and transmittance thereof may be 90% or more.
- the thermal treatment may be performed as an extrusion operation.
- the extrusion operation may be performed by performing a re-extrusion two to five times by using a twin screw extruder.
- the extrusion operation may be performed in vacuum at a pressure lower than 40 torr.
- a method for fabricating an optical film including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare an acrylic copolymer; thermally treating the acrylic copolymer at a temperature ranging from 240° C. to 300° C.; extruding the acrylic copolymer to fabricate a film; and stretching the film.
- the operation for preparing the acrylic copolymer may be the same as described above, and thermally treating the acrylic copolymer and extruding the acrylic copolymer to fabricate a film may be performed as a single operation.
- the extrusion operation may be performed by performing a re-extrusion two to five times by using a twin screw extruder.
- the film may be stretched in a vertical direction (i.e., in a mechanical direction (MD)) so as to be double and then stretched biaxially in a horizontal direction (i.e., in a transverse direction (TD)) so as to be triple.
- MD mechanical direction
- TD transverse direction
- the optical film having an in-plane retardation value represented by Equation 1 shown below and a thickness retardation value represented by Equation 2 shown below may range from ⁇ 5 to 5 nm respectively:
- R in ( n x ⁇ n y ) ⁇ d [Equation 1]
- R th ( n z ⁇ n y ) ⁇ d [Equation 2]
- n x is a refractive index in a direction in which the refractive index is the greatest in the in-plane direction
- n y is a refractive index in a direction perpendicular to the n x direction in the in-plane direction
- n z is a refractive index in a thicknesswise direction
- d is the thickness of the film.
- the optical film may have a coefficient of thermal expansion (CTE) of 70 ppm/° C. or lower.
- a resin having an effectively lowered CTE and an optical film can be manufactured by inducing the formation of a glutaric anhydride structure by using suspension polymerization that facilitates adjustment of the molecular weight of a resin.
- An aspect of the present invention provides a method for preparing an acrylic copolymer resin for an optical film, including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare a copolymer; and thermally treating the copolymer at a temperature ranging from 240° C. to 300° C.
- the copolymer may be a block copolymer or a random copolymer, but the form of the copolymer is not limited thereto.
- suspension polymerization includes any suspension polymerization methods generally used in the related art.
- a suspension polymerization method a raw material monomer is dispersed in an immiscible liquid such as water and polymerized by adding an initiator, or the like, thereto. With this method, heat generated as a polymer is polymerized is transferred to the immiscible liquid, facilitating controlling of heating and adjusting of molecular weight in relation to toughness.
- an immerscible liquid that may be used in an embodiment of the present invention is water.
- the suspension-polymerization operation may be performed by including a first polymerization operation of performing suspension polymerization at an initial reaction temperature ranging from 60° C. to 90° C. for two to three hours and a second polymerization operation of increasing the temperature to 80° C. to 100° C. and additionally performing polymerization for one to two hours.
- the first polymerization operation of performing suspension polymerization at the initial reaction temperature satisfies a condition of an initiator used in the related art. If the initial reaction temperature is lower than 60° C., it may not be able to effectively secure a polymerization conversion ratio, and if the initial reaction temperature exceeds 90° C., there may be a problem in controlling an initial reaction such as heat controlling.
- a reaction temperature may be set according to a half-life of the initiator and a reaction duration may be adjusted to be two to three hours.
- the reaction duration is related to efficiency, which is not particularly limited so long as it is within a range in which an appropriate polymerization level is obtainable; however, since it is more effective as the reaction duration is shorter, the reaction duration may be two to three hours.
- the conversion ratio may be enhanced by the second polymerization operation in which the temperature is increased and polymerization is additionally performed.
- the temperature in the second polymerization operation may be increased to be higher by about 5° C. to 20° C., preferably, by 10° C., based on the initial polymerization temperature in the aspect of completing the polymerization of an unreacted monomer.
- the second polymerization operation is preferably performed at a temperature ranging from 80° C. to 100° C.
- the reaction duration is one to two hours.
- a resin in order to enhance toughness of a stretched film, a resin is prepared by using suspension polymerization facilitating the adjustment of molecular weight of the resin, and since the heat treatment operation is included, a formation of glutaric anhydride may be induced by providing thermal history to the resin.
- the prepared copolymer is heated to a temperature ranging from 240° C. to 300° C., and preferably, to a temperature ranging from 260° C. to 290° C. If the temperature for the thermal treatment operation is lower than 240° C., glutaric anhydride may not be effectively generated, and if the temperature for the thermal treatment operation exceeds 300° C., there may be a problem with stability in relation to resin decomposition.
- the thermal treatment operation may be performed as an extrusion operation. Namely, it is preferable in terms of process that the copolymer obtained in the form of granule according to the outcome of the suspension polymerization is hot-extruded at a temperature ranging from 240° C. to 300° C. so as to be prepared.
- the copolymer is re-extruded two to five times by using a twin screw extruder, but the number of re-extrusions may vary, depending on the temperature and the length of the extruder, and an amount of extrusions exceeding five times is not desirable in terms of stability, according to resin degradation.
- the copolymer is re-extruded two or more times by using the twin screw extruder with the screws having a length of about 1 m, but a single extrusion may be performed according to a provided temperature range and device, or a single screw extruder may be used under conditions in which heat transmission and extrusion are effectively performed.
- the extrusion process may be preferably performed in a vacuum state, and more preferably, performed in a state in which the degree of vacuum is less than 40 torr. Since, in an embodiment of the present invention, glutaric anhydride is generated through the foregoing extrusion process, a higher efficiency than a case in which methanol, or the like, generated in the conversion reaction is removed in a vacuum can be obtained.
- the acrylic copolymer resin including (meth)acrylic acid monomer is thermally treated to induce a generation of glutaric anhydride, thus lowering the coefficient of thermal expansion of the resin.
- the acrylic copolymer resin for an optical film prepared as described above may be in a pellet state, and include glutaric anhydride.
- the glutaric anhydride unit is generated as an alkyl(meth)acrylate unit and/or an acrylic unit containing a benzene ring, and a (meth)acrylic acid unit react according to the thermal treatment after the preparation of the copolymer.
- the content of the glutaric anhydride unit within the finally obtained acrylic copolymer for an optical film can be adjusted by regulating the content of the (meth)acrylic acid monomer applied for polymerization and the degree of thermal treatment.
- ‘unit’ is used to designate a corresponding component that does not exist in the form of a monomer in a case in which a monomer is polymerized to form a copolymer.
- the four-composite copolymer including the glutaric anhydride unit has an effect of reducing the coefficient of thermal expansion, which is not found in the three-composite copolymer including the alkyl(meth)acrylate monomer, the acrylic monomer containing a benzene ring, and the (meth)acrylic acid monomer, while maintaining the same excellent retardation characteristics as those of the three-composite copolymer. This is because macromolecule chain rotation is limited by a bulky functional group of the glutaric anhydride.
- the content of the monomers added for polymerization is 3 to 15 weight parts of an acrylic monomer containing the benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate monomer, and 5 to 20 weight parts of a (meth)acrylic acid monomer.
- the acrylic monomer containing the benzene rings When the acrylic monomer containing the benzene rings is out of the given range, there may be a problem in adjusting a retardation of a protective film. Also, if the (meth)acrylic acid monomer is less than 5 weight parts, the content of the generated glutaric anhydride may be insufficient to lower the coefficient of thermal expansion, and if the (meth)acrylic acid monomer exceeds 20 weight parts, thermal stability of the final resin may be increased, resulting in a film becoming brittle when fabricated.
- the acrylic monomer containing the benzene ring serves to adjust the retardation in in-plane or thickness directions, such that the acrylic copolymer resin according to an embodiment of the present invention can be appropriately applied as a polarizer protective film.
- the acrylic monomer containing the benzene ring may be substituted with an aryl group having 6 to 40 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, an aryloxy group having 6 to 40 carbon atoms, or an aryloxyalkyl group having 6 to 40 carbon atoms.
- the acrylic monomer containing the benzene ring may be (meth)acrylate substituted with an arylalkyl group having 6 to 15 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, or an aryloxyalkyl group having 6 to 15 carbon atoms in terms of transparency.
- Preferred examples of the acrylic monomer containing a benzene ring may be selected from the group consisting of benzyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, 2-phenylethyl methacrylate, 3-phenylpropyl methacrylate, 3-phenylpropyl acrylate, and 2-phenoxyethyl acrylate.
- the acrylic monomer containing the benzene ring may be benzyl methacrylate.
- alkyl(meth)acrylate monomer may refer to both an ‘alkylacrylate monomer’ and an ‘alkylmethacrylate monomer’.
- the alkyl group of the alkyl(meth)acrylate monomer has, preferably, 1 to 10 carbon atoms, more preferably, 1 to 4 carbon atoms, and more preferably, is a methyl group or an ethyl group.
- the alkyl(meth)acrylate monomer may include methylacrylate, ethylacrylate, methylmethacrylate, ethylmethacrylate, methylethacryate, ethylethacrylate, and the like. Among them, methylmethacrylate is the most preferable, but the present invention is not limited thereto.
- the ‘(meth)acrylic acid monomer’ refers to the inclusion of an ‘acrylic acid monomer’ and a ‘methacrylic acid monomer’.
- the (meth)acrylic acid monomer allows the acrylic copolymer resin according to an embodiment of the present invention to have sufficient thermal stability, and induces generation of glutaric anhydride to thus lower the coefficient of thermal expansion of the resin.
- the (meth)acrylic acid monomer may be substituted with an alkyl group having 1 to 5 carbon atoms, or may be unsubstituted.
- the (meth)acrylic acid monomer may be, for example, acrylic acid, methacrylic acid, methylacryl acid, methylmethacrylic acid, ethylacrylic acid, ethylmethacrylic acid, butylacrylic acid, butylmethacrylic acid, or the like. Among these, the use of methacrylic acid is most economical.
- the acrylic copolymer resin for an optical film obtained through the foregoing preparation method includes 3 to 15 weight parts of an acrylic unit containing a benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate unit, 0 to 4 weight parts of a (meth)acrylic acid unit, and 5 to 16 weight parts of a glutaric anhydride unit.
- the copolymer resin may not be effective to lower the coefficient of thermal expansion, and in order to prepare the copolymer resin in which the content of glutaric anhydride exceeds 16 weight parts over 100 weight parts of the overall copolymer resin, the content of acrylic acid may be required to be increased. In this case, however, thermal stability may be increased to be so high as to make the final film brittle. Thus, preferably, a great deal of acrylic acid is converted into glutaric anhydride, after polymerization, to lower the coefficient of thermal expansion.
- a weight-average molecular weight of the acrylic copolymer resin preferably ranges from 50000 to 500000 in terms of thermal stability, processibility, and productivity, and more preferably, from 50000 to 200000.
- a glass transition temperature Tg of the acrylic copolymer resin may preferably be 120° C. or higher, and more preferably, 125° C. or higher.
- a method for fabricating an optical film including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare an acrylic copolymer; thermally treating the acrylic copolymer at a temperature ranging from 240° C. to 300° C.; extruding the acrylic copolymer to fabricate a film; and stretching the film.
- the thermally treating and the extruding the acrylic copolymer to fabricate a film are performed as a single operation. Namely, it is preferable, in terms of process, that a copolymer obtained in the form of granules according to the outcome of the suspension polymerization is hot-extruded at a temperature ranging from 240° C. to 300° C. to fabricate a film.
- a film may be fabricated with the acrylic copolymer resin by a method well known in the art such as a caster method, or the like, but the extrusion method, which is economical, is desirous.
- the copolymer is re-extruded two to five times by using a twin screw extruder, but a single extrusion may be performed according to a provided temperature range and device, or a single screw extruder may be used under conditions in which heat transmission and extrusion are effectively performed.
- uni-axially or bi-axially stretching the film may be additionally performed.
- stretching in a mechanical direction (MD) (or a vertical direction) and stretching in a transverse direction (TD) (or a horizontal direction) may be separately performed, or both may be performed together.
- MD mechanical direction
- TD transverse direction
- any one of vertical stretching and horizontal stretching may first be performed and then the stretching in the other direction may be performed.
- vertical and horizontal stretching may be simultaneously performed. Stretching may be performed in a single stage or in multiple stages. In the case of vertical stretching, the stretching may be performed according to difference between the speeds of rollers, and in the case of horizontal stretching, a tenter may be used.
- a rail initiation angle of the tenter is generally within 10 degrees to restrain a bowing phenomenon occurring in the event of horizontal stretching, and to control the angle of an optical axis regularly.
- the same bowing restraining effect can also be obtained by performing multistage horizontal stretching.
- the film may be stretched in a vertical direction (i.e., in a mechanical direction (MD)) so as to be double and then stretched biaxially in a horizontal direction (i.e., in a transverse direction (TD)) so as to be triple.
- MD mechanical direction
- TD transverse direction
- a conditioner may be added according to circumstances, to fabricate a film.
- the stretching may be performed at a temperature ranging from (Tg ⁇ 20° C.) ⁇ (Tg+30° C.).
- the glass transition temperature refers to a temperature range starting from a temperature at which a storage modulus of the copolymer resin starts to be lowered so a loss modulus starts to be increased to be greater than the storage modulus to a temperature at which orientation of polymer chains is lessened to be lost.
- the glass transition temperature may be measured by a differential scanning calorimetry (DSC).
- DSC differential scanning calorimetry
- the temperature at the time of the stretching process may be a glass transition temperature of the film.
- the optical film fabricated as described above having an in-plane retardation value represented by Equation 1 shown below and a thickness retardation value represented by Equation 2 shown below may range from ⁇ 5 to 5 nm.
- R in ( n x ⁇ n y ) ⁇ d [Equation 1]
- R th ( n z ⁇ n y ) ⁇ d [Equation 2]
- n x is a refractive index in a direction in which the refractive index is the greatest in the in-plane direction
- n y is a refractive index in a direction perpendicular to the n x direction in the in-plane direction
- n z is a refractive index in a thicknesswise direction
- d is the thickness of the film.
- the thickness of the optical film fabricated as described above may range from 20 to 200 ⁇ m, preferably, range from 40 to 120 ⁇ m, and have transparency (haze) ranging from 0.1 to 1% and transmittance of 90% or more.
- the optical film has a coefficient of thermal expansion (CTE) of 70 ppm/° C. or lower.
- CTE coefficient of thermal expansion
- the thickness, transparency, and transmittance of the film are within the foregoing ranges, in case of using the optical film according to an embodiment of the present invention as a protective film of a polarizer, image quality is not degraded.
- MMA methyl methacrylate
- BzMA benzyl methacrylate
- MAA methacrylic acid
- the prepared mixture was primarily suspension-polymerized at an initial reaction temperature of 80° C. for two hours, and then, the temperature was raised to 95° C. to perform secondary polymerization on the resultant material for one hour.
- the resultant material was then cleansed and dried to fabricate MMA-BzMA-MAA beads.
- the obtained beads were re-extruded twice through a co-rotating twin screw extruder at 270° C. to prepare a resin in a state of pellet, and at this time, the degree of vacuum (Torr) was 20.
- the composition of the final resin is shown in Table 1 below and the physical properties of the final resin are shown in Table 3 below.
- an extruded film having a thickness of 180 ⁇ m was fabricated by using an extruder including a T-die.
- the fabricated film was stretched in a mechanical direction (MD) so as to be double and then stretched biaxially in a transverse direction (TD) so as to be triple, thus fabricating a film having a thickness of 60 ⁇ m, and TAC and PVA were bonded to the film to fabricate a polarization plate.
- MD mechanical direction
- TD transverse direction
- MMA methyl methacrylate
- BzMA benzyl methacrylate
- MAA methacrylic acid
- MMA methyl methacrylate
- BzMA benzyl methacrylate
- MAA methacrylic acid
- MMA methyl methacrylate
- BzMA benzyl methacrylate
- MAA methacrylic acid
- MMA methyl methacrylate
- BzMA benzyl methacrylate
- a resin was prepared through the same process as that of Embodiment 1.
- the composition of the final resin is shown in Table 1, the physical properties of the final resin are shown in Table 3, and the physical properties of the film are shown in Table 5.
- MMA methyl methacrylate
- BzMA benzyl methacrylate
- MAA methacrylic acid
- MMA methyl methacrylate
- BzMA benzyl methacrylate
- MAA methacrylic acid
- MMA methyl methacrylate
- BzMA benzyl methacrylate
- MAA methacrylic acid
- compositions of the final resins and physical evaluation method of the final resin were as follows.
- Weight-average molecular weight (Mw) The prepared resin was dissolved in tetrahydropurane and measured by using gel permeation chromatography (GPC).
- Tg Glass transition temperature
- Haze and light transmittance Measured based on an ASTM 1003 method.
- a method for evaluating the physical properties of the film according to an embodiment of the present invention is as follows.
- Retardation value (R in , R th ): Measured by using an Elli-SE from Ellipso Tech. Co., Ltd.
- Toughness Measured by bending a 60 ⁇ m film ten times by hand to check whether or not it would break ( ⁇ : unbroken, ⁇ : broken one to three times, x: broken five or more times)
- the CTE can be lowered while satisfying the basic conditions with respect to the polarizer protective film such as retardations by polymerizing using particular compositions and contents of monomers and performing a thermal treatment thereupon.
Landscapes
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Medicinal Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Optics & Photonics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Polymerisation Methods In General (AREA)
- Polarising Elements (AREA)
Abstract
There is provided a method for preparing an acrylic copolymer resin for an optical film includes: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare a copolymer; and thermally treating the copolymer at a temperature ranging from 240° C. to 300° C. As the method for preparing an acrylic copolymer of the present invention, a resin having an effectively lowered CTE can be manufactured by inducing the formation of a glutaric anhydride structure by using suspension polymerization that facilitates adjustment of the molecular weight of a resin.
Description
This application is a National Phase Entry of International Application No. PCT/KR2012/000869, filed Feb. 7, 2012, and claims priority to and the benefit of Korean Patent Application Nos. 10-2011-0034443, filed Apr. 13, 2011, and 10-2011-0083999, filed Aug. 23, 2011, the disclosures of which are incorporated herein by reference in their entirety.
The present invention relates to a method for preparing a resin for an optical film and, more particularly, to a method for fabricating an acrylic copolymer resin having excellent thermal stability.
Recently, based on the development of optical technologies, display techniques using various schemes, such as a plasma display panel (PDP), a liquid crystal display (LCD), and the like, replacing the conventional Cathode Ray Tube, have been proposed and have become available on the market.
Advanced level requirements are required for a polymer material used for such displays. For example, in case of LCDs, as LCDs are becoming thinner, lighter, and larger in terms of screen area, obtaining a wide viewing angle and a high contrast ratio, suppressing of a change in an image color according to a viewing angle, and making a screen display uniform have become particularly significant issues.
Accordingly, various polymer films are used for a polarization film, a polarizer protective film, a retardation film, a plastic substrate, a light guide plate, and the like, and various modes of LCD devices using twisted nematic (TN), super-twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS) liquid crystal cells, and the like, as liquid crystal have been developed. These liquid crystal cells have a unique liquid crystal arrangement, respectively having a unique optical anisotropy, and, in order to compensate for the optical anisotropy, films obtained by stretching various types of polymers and providing retardation function thereto have been proposed.
A polarization plate generally has a structure in which a triacetyl cellulose film (TAC) film is laminated on a polarizer as a protective film, using a water-based adhesive made of a polyvinylalcohol-based aqueous solution. In this respect, however, neither the polyvinylalcohol film used as a polarizer nor the TAC film used as a polarizer protective film have sufficient heat and moisture resistance. Thus, when the polarization plate comprised of the films is used for a long period of time in high temperature or high moisture conditions, the degree of polarization may be degraded, the polarizer and the protective film may be separated, and optical characteristics may be degraded, such that the polarization plate is variably restricted in terms of the purpose thereof.
Also, the TAC film has an in-plane retardation value (Rin) and a thickness retardation value (Rth) which are severely changed according to changes in ambient temperature and moisture in the surrounding environment, and, in particular, a retardation value with respect to incident light in a tilt direction is greatly varied. Thus, an application of the polarization plate including the TAC film having the foregoing characteristics as a protective film to an LCD device would result in a degradation of image quality due to the viewing angle characteristics thereof being changed according to a change in the ambient temperature and moisture environment.
Also, the TAC film has a great dimensional variation according to changes in ambient temperature and moisture environments and a relatively high photoelastic coefficient value. Thus, after an evaluation of durability in a heat-resistant, moisture resistant environment, retardation characteristics may be changed locally to thereby degrade image quality. An acrylic resin has been well known as a material for complementing the various shortcomings of the TAC film. However, the acrylic resin does not have sufficient heat resistance characteristics, and creates a retardation in in-plane and thickness directions after being stretched, and therefore is not appropriate to be applied as a protective film.
Thus, in order to solve the problem of the related art, a method for preparing an acrylic copolymer resin having little retardation in the in-plane and thickness directions, a small photoelastic coefficient, and excellent heat resistance, even after being stretched, to be used as a polarizer protective film, is required.
An aspect of the present invention provides a method for preparing an acrylic copolymer resin having excellent thermal stability, transparency, and optical physical properties.
According to an aspect of the present invention, there is provided a method for preparing an acrylic copolymer resin for an optical film, including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare an acrylic copolymer; and thermally treating the copolymer at a temperature ranging from 240° C. to 300° C.
The suspension-polymerizing may include: a first polymerization operation of performing suspension polymerization at an initial reaction temperature ranging from 60° C. to 90° C. for two to three hours; and a second polymerization operation of increasing the temperature by 5° C. to 20° C., based on the temperature of the first polymerization operation, and additionally performing polymerization for one to two hours.
For example, the second polymerization operation may be performed at a temperature ranging from 80° C. to 100° C.
In the preparing of the acrylic copolymer, 3 to 15 weight parts of an acrylic monomer containing a benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate monomer, and 5 to 20 weight parts of a (meth)acrylic acid monomer may be suspension-polymerized.
In the preparing of the acrylic copolymer, 3 to 15 weight parts of a benzylmethacrylate, 65 to 92 weight parts of a methylmethacrylate monomer, and 5 to 20 weight parts of a methacrylic acid monomer may be suspension-polymerized.
The acrylic monomer containing a benzene ring may be selected from the group consisting of benzyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, 2-phenylethyl methacrylate, 3-phenylpropyl methacrylate, 3-phenylpropyl acrylate, and 2-phenoxyethyl acrylate.
The alkyl group of the alkyl(meth)acrylate monomer may have 1 to 10 carbon atoms.
The alkyl(meth)acrylate monomer may be selected from the group consisting of methylacrylate, ethylacrylate, methylmethacrylate, ethylmethacrylate, methylethacryate, and ethylethacrylate.
The (meth)acrylic acid monomer may be selected from the group consisting of acrylic acid, methacrylic acid, methylacryl acid, methylmethacrylic acid, ethylacrylic acid, ethylmethacrylic acid, butylacrylic acid, and butylmethacrylic acid.
The acrylic copolymer resin for an optical film obtained by the preparation method may include glutaric anhydride.
The acrylic copolymer resin for an optical film obtained through the preparation method may include 3 to 15 weight parts of an acrylic unit containing a benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate unit, 0 to 4 weight parts of a (meth)acrylic acid unit, and 5 to 16 weight parts of a glutaric anhydride unit, over 100 weight parts of the acrylic copolymer resin.
A glass transition temperature of the acrylic copolymer resin may be 120° C. or higher.
Haze of the acrylic copolymer resin may range from 0.1 to 1%, and transmittance thereof may be 90% or more.
The thermal treatment may be performed as an extrusion operation.
The extrusion operation may be performed by performing a re-extrusion two to five times by using a twin screw extruder.
The extrusion operation may be performed in vacuum at a pressure lower than 40 torr.
According to another aspect of the present invention, there is provided a method for fabricating an optical film, including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare an acrylic copolymer; thermally treating the acrylic copolymer at a temperature ranging from 240° C. to 300° C.; extruding the acrylic copolymer to fabricate a film; and stretching the film.
The operation for preparing the acrylic copolymer may be the same as described above, and thermally treating the acrylic copolymer and extruding the acrylic copolymer to fabricate a film may be performed as a single operation.
The extrusion operation may be performed by performing a re-extrusion two to five times by using a twin screw extruder.
In the stretching operation, the film may be stretched in a vertical direction (i.e., in a mechanical direction (MD)) so as to be double and then stretched biaxially in a horizontal direction (i.e., in a transverse direction (TD)) so as to be triple.
The optical film having an in-plane retardation value represented by Equation 1 shown below and a thickness retardation value represented by Equation 2 shown below may range from −5 to 5 nm respectively:
R in=(n x −n y)×d [Equation 1]
R th=(n z −n y)×d [Equation 2]
R in=(n x −n y)×d [Equation 1]
R th=(n z −n y)×d [Equation 2]
In Equation 1 and Equation 2, nx is a refractive index in a direction in which the refractive index is the greatest in the in-plane direction, ny is a refractive index in a direction perpendicular to the nx direction in the in-plane direction, nz is a refractive index in a thicknesswise direction, and d is the thickness of the film.
The optical film may have a coefficient of thermal expansion (CTE) of 70 ppm/° C. or lower.
As set forth above, with the method for preparing an acrylic copolymer resin and a method for fabricating an optical film using the same according to the present invention, a resin having an effectively lowered CTE and an optical film can be manufactured by inducing the formation of a glutaric anhydride structure by using suspension polymerization that facilitates adjustment of the molecular weight of a resin.
An aspect of the present invention provides a method for preparing an acrylic copolymer resin for an optical film, including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare a copolymer; and thermally treating the copolymer at a temperature ranging from 240° C. to 300° C.
The copolymer may be a block copolymer or a random copolymer, but the form of the copolymer is not limited thereto.
In an embodiment of the present invention, preparation of an acrylic copolymer may use suspension polymerization, and here, suspension polymerization includes any suspension polymerization methods generally used in the related art. For example, in a suspension polymerization method, a raw material monomer is dispersed in an immiscible liquid such as water and polymerized by adding an initiator, or the like, thereto. With this method, heat generated as a polymer is polymerized is transferred to the immiscible liquid, facilitating controlling of heating and adjusting of molecular weight in relation to toughness. Preferably, an immerscible liquid that may be used in an embodiment of the present invention is water.
Preferably, the suspension-polymerization operation may be performed by including a first polymerization operation of performing suspension polymerization at an initial reaction temperature ranging from 60° C. to 90° C. for two to three hours and a second polymerization operation of increasing the temperature to 80° C. to 100° C. and additionally performing polymerization for one to two hours.
The first polymerization operation of performing suspension polymerization at the initial reaction temperature satisfies a condition of an initiator used in the related art. If the initial reaction temperature is lower than 60° C., it may not be able to effectively secure a polymerization conversion ratio, and if the initial reaction temperature exceeds 90° C., there may be a problem in controlling an initial reaction such as heat controlling. In the first polymerization operation, a reaction temperature may be set according to a half-life of the initiator and a reaction duration may be adjusted to be two to three hours. The reaction duration is related to efficiency, which is not particularly limited so long as it is within a range in which an appropriate polymerization level is obtainable; however, since it is more effective as the reaction duration is shorter, the reaction duration may be two to three hours.
Thereafter, the conversion ratio may be enhanced by the second polymerization operation in which the temperature is increased and polymerization is additionally performed. The temperature in the second polymerization operation may be increased to be higher by about 5° C. to 20° C., preferably, by 10° C., based on the initial polymerization temperature in the aspect of completing the polymerization of an unreacted monomer. Specifically, the second polymerization operation is preferably performed at a temperature ranging from 80° C. to 100° C. If the additional polymerization operation is performed at a temperature lower than 80° C., efficiency in completing the polymerization may be degraded, and if the additional polymerization operation is performed at a temperature higher than 100° C., it may be difficult to control a reaction such as a rise in temperature. Preferably, in terms of efficiency, the reaction duration is one to two hours.
In an embodiment of the present invention, in order to enhance toughness of a stretched film, a resin is prepared by using suspension polymerization facilitating the adjustment of molecular weight of the resin, and since the heat treatment operation is included, a formation of glutaric anhydride may be induced by providing thermal history to the resin.
In the thermal treatment operation of the present embodiment, the prepared copolymer is heated to a temperature ranging from 240° C. to 300° C., and preferably, to a temperature ranging from 260° C. to 290° C. If the temperature for the thermal treatment operation is lower than 240° C., glutaric anhydride may not be effectively generated, and if the temperature for the thermal treatment operation exceeds 300° C., there may be a problem with stability in relation to resin decomposition.
In the case of the suspension polymerization, since there may be a limitation in the process of applying heat as water is used, and since the resin is obtained through a dehydration process, the thermal treatment operation may be performed as an extrusion operation. Namely, it is preferable in terms of process that the copolymer obtained in the form of granule according to the outcome of the suspension polymerization is hot-extruded at a temperature ranging from 240° C. to 300° C. so as to be prepared. In this case, more preferably, the copolymer is re-extruded two to five times by using a twin screw extruder, but the number of re-extrusions may vary, depending on the temperature and the length of the extruder, and an amount of extrusions exceeding five times is not desirable in terms of stability, according to resin degradation.
In particular, preferably, the copolymer is re-extruded two or more times by using the twin screw extruder with the screws having a length of about 1 m, but a single extrusion may be performed according to a provided temperature range and device, or a single screw extruder may be used under conditions in which heat transmission and extrusion are effectively performed.
Meanwhile, the extrusion process may be preferably performed in a vacuum state, and more preferably, performed in a state in which the degree of vacuum is less than 40 torr. Since, in an embodiment of the present invention, glutaric anhydride is generated through the foregoing extrusion process, a higher efficiency than a case in which methanol, or the like, generated in the conversion reaction is removed in a vacuum can be obtained.
In general, when a film is fabricated by using an acrylic copolymer resin and laminated with a TAC film, or the like, to fabricate a polarization plate, a curling phenomenon in which the polarization plate is bent or distorted due to the difference between the coefficients of thermal expansion of the two films occurs. However, in an embodiment of the present invention, the acrylic copolymer resin including (meth)acrylic acid monomer is thermally treated to induce a generation of glutaric anhydride, thus lowering the coefficient of thermal expansion of the resin.
The acrylic copolymer resin for an optical film prepared as described above may be in a pellet state, and include glutaric anhydride.
The glutaric anhydride unit is generated as an alkyl(meth)acrylate unit and/or an acrylic unit containing a benzene ring, and a (meth)acrylic acid unit react according to the thermal treatment after the preparation of the copolymer. The content of the glutaric anhydride unit within the finally obtained acrylic copolymer for an optical film can be adjusted by regulating the content of the (meth)acrylic acid monomer applied for polymerization and the degree of thermal treatment. In the present disclosure, ‘unit’ is used to designate a corresponding component that does not exist in the form of a monomer in a case in which a monomer is polymerized to form a copolymer.
The four-composite copolymer including the glutaric anhydride unit has an effect of reducing the coefficient of thermal expansion, which is not found in the three-composite copolymer including the alkyl(meth)acrylate monomer, the acrylic monomer containing a benzene ring, and the (meth)acrylic acid monomer, while maintaining the same excellent retardation characteristics as those of the three-composite copolymer. This is because macromolecule chain rotation is limited by a bulky functional group of the glutaric anhydride.
Preferably, the content of the monomers added for polymerization is 3 to 15 weight parts of an acrylic monomer containing the benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate monomer, and 5 to 20 weight parts of a (meth)acrylic acid monomer.
When the acrylic monomer containing the benzene rings is out of the given range, there may be a problem in adjusting a retardation of a protective film. Also, if the (meth)acrylic acid monomer is less than 5 weight parts, the content of the generated glutaric anhydride may be insufficient to lower the coefficient of thermal expansion, and if the (meth)acrylic acid monomer exceeds 20 weight parts, thermal stability of the final resin may be increased, resulting in a film becoming brittle when fabricated.
The acrylic monomer containing the benzene ring serves to adjust the retardation in in-plane or thickness directions, such that the acrylic copolymer resin according to an embodiment of the present invention can be appropriately applied as a polarizer protective film. The acrylic monomer containing the benzene ring may be substituted with an aryl group having 6 to 40 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, an aryloxy group having 6 to 40 carbon atoms, or an aryloxyalkyl group having 6 to 40 carbon atoms. Preferably, the acrylic monomer containing the benzene ring may be (meth)acrylate substituted with an arylalkyl group having 6 to 15 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, or an aryloxyalkyl group having 6 to 15 carbon atoms in terms of transparency.
Preferred examples of the acrylic monomer containing a benzene ring may be selected from the group consisting of benzyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, 2-phenylethyl methacrylate, 3-phenylpropyl methacrylate, 3-phenylpropyl acrylate, and 2-phenoxyethyl acrylate. Most preferably, the acrylic monomer containing the benzene ring may be benzyl methacrylate.
In the present disclosure, ‘alkyl(meth)acrylate monomer’ may refer to both an ‘alkylacrylate monomer’ and an ‘alkylmethacrylate monomer’. When optical transparency, compatibility with different resins, processibility, and productivity are taken into consideration, the alkyl group of the alkyl(meth)acrylate monomer has, preferably, 1 to 10 carbon atoms, more preferably, 1 to 4 carbon atoms, and more preferably, is a methyl group or an ethyl group.
In detail, the alkyl(meth)acrylate monomer may include methylacrylate, ethylacrylate, methylmethacrylate, ethylmethacrylate, methylethacryate, ethylethacrylate, and the like. Among them, methylmethacrylate is the most preferable, but the present invention is not limited thereto.
In the present disclosure, the ‘(meth)acrylic acid monomer’ refers to the inclusion of an ‘acrylic acid monomer’ and a ‘methacrylic acid monomer’. The (meth)acrylic acid monomer allows the acrylic copolymer resin according to an embodiment of the present invention to have sufficient thermal stability, and induces generation of glutaric anhydride to thus lower the coefficient of thermal expansion of the resin.
The (meth)acrylic acid monomer may be substituted with an alkyl group having 1 to 5 carbon atoms, or may be unsubstituted. The (meth)acrylic acid monomer may be, for example, acrylic acid, methacrylic acid, methylacryl acid, methylmethacrylic acid, ethylacrylic acid, ethylmethacrylic acid, butylacrylic acid, butylmethacrylic acid, or the like. Among these, the use of methacrylic acid is most economical.
Meanwhile, preferably, the acrylic copolymer resin for an optical film obtained through the foregoing preparation method includes 3 to 15 weight parts of an acrylic unit containing a benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate unit, 0 to 4 weight parts of a (meth)acrylic acid unit, and 5 to 16 weight parts of a glutaric anhydride unit.
When the glutaric anhydride is less than 5 weight parts over 100 weight parts of the overall copolymer resin, the copolymer resin may not be effective to lower the coefficient of thermal expansion, and in order to prepare the copolymer resin in which the content of glutaric anhydride exceeds 16 weight parts over 100 weight parts of the overall copolymer resin, the content of acrylic acid may be required to be increased. In this case, however, thermal stability may be increased to be so high as to make the final film brittle. Thus, preferably, a great deal of acrylic acid is converted into glutaric anhydride, after polymerization, to lower the coefficient of thermal expansion.
A weight-average molecular weight of the acrylic copolymer resin preferably ranges from 50000 to 500000 in terms of thermal stability, processibility, and productivity, and more preferably, from 50000 to 200000.
A glass transition temperature Tg of the acrylic copolymer resin may preferably be 120° C. or higher, and more preferably, 125° C. or higher.
According to an embodiment of the present invention, there is provided a method for fabricating an optical film, including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare an acrylic copolymer; thermally treating the acrylic copolymer at a temperature ranging from 240° C. to 300° C.; extruding the acrylic copolymer to fabricate a film; and stretching the film.
The suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare an acrylic copolymer, and thermally treating the acrylic copolymer at a temperature ranging from 240° C. to 300° C. have previously been described.
Preferably, the thermally treating and the extruding the acrylic copolymer to fabricate a film are performed as a single operation. Namely, it is preferable, in terms of process, that a copolymer obtained in the form of granules according to the outcome of the suspension polymerization is hot-extruded at a temperature ranging from 240° C. to 300° C. to fabricate a film.
A film may be fabricated with the acrylic copolymer resin by a method well known in the art such as a caster method, or the like, but the extrusion method, which is economical, is desirous. In the extruding operation, preferably, the copolymer is re-extruded two to five times by using a twin screw extruder, but a single extrusion may be performed according to a provided temperature range and device, or a single screw extruder may be used under conditions in which heat transmission and extrusion are effectively performed.
In case of fabricating an optical film by using the acrylic copolymer resin of the present invention, uni-axially or bi-axially stretching the film may be additionally performed. As for the stretching process, stretching in a mechanical direction (MD) (or a vertical direction) and stretching in a transverse direction (TD) (or a horizontal direction) may be separately performed, or both may be performed together. When both vertical and horizontal stretching operations are performed, any one of vertical stretching and horizontal stretching may first be performed and then the stretching in the other direction may be performed. Alternatively, vertical and horizontal stretching may be simultaneously performed. Stretching may be performed in a single stage or in multiple stages. In the case of vertical stretching, the stretching may be performed according to difference between the speeds of rollers, and in the case of horizontal stretching, a tenter may be used. A rail initiation angle of the tenter is generally within 10 degrees to restrain a bowing phenomenon occurring in the event of horizontal stretching, and to control the angle of an optical axis regularly. The same bowing restraining effect can also be obtained by performing multistage horizontal stretching. In the stretching operation, preferably, the film may be stretched in a vertical direction (i.e., in a mechanical direction (MD)) so as to be double and then stretched biaxially in a horizontal direction (i.e., in a transverse direction (TD)) so as to be triple. A conditioner may be added according to circumstances, to fabricate a film.
When a glass transition temperature of the copolymer resin is Tg, the stretching may be performed at a temperature ranging from (Tg−20° C.)˜(Tg+30° C.). The glass transition temperature refers to a temperature range starting from a temperature at which a storage modulus of the copolymer resin starts to be lowered so a loss modulus starts to be increased to be greater than the storage modulus to a temperature at which orientation of polymer chains is lessened to be lost. The glass transition temperature may be measured by a differential scanning calorimetry (DSC). Preferably, the temperature at the time of the stretching process may be a glass transition temperature of the film.
The optical film fabricated as described above having an in-plane retardation value represented by Equation 1 shown below and a thickness retardation value represented by Equation 2 shown below may range from −5 to 5 nm.
R in=(n x −n y)×d [Equation 1]
R th=(n z −n y)×d [Equation 2]
R in=(n x −n y)×d [Equation 1]
R th=(n z −n y)×d [Equation 2]
In Equation 1 and Equation 2, nx is a refractive index in a direction in which the refractive index is the greatest in the in-plane direction, ny is a refractive index in a direction perpendicular to the nx direction in the in-plane direction, nz is a refractive index in a thicknesswise direction, and d is the thickness of the film.
The thickness of the optical film fabricated as described above may range from 20 to 200 μm, preferably, range from 40 to 120 μm, and have transparency (haze) ranging from 0.1 to 1% and transmittance of 90% or more.
Meanwhile, preferably, the optical film has a coefficient of thermal expansion (CTE) of 70 ppm/° C. or lower. When the CTE exceeds 70 ppm/° C., curling may be generated when the polarization plate is laminated.
When the thickness, transparency, and transmittance of the film are within the foregoing ranges, in case of using the optical film according to an embodiment of the present invention as a protective film of a polarizer, image quality is not degraded.
Hereinafter, the present invention will be described in detail through the following embodiments. However, the following embodiments are merely illustrative, and the scope of the present invention is not intended to be limited by the following embodiments.
A mixture obtained by mixing 0.05 weight parts of 5% polyvinylalcohol aqueous solution, 200 weight parts of water, 0.08 weight parts of t-hexyl peroxy-2-ethylhexanoate as an initiator, 0.2 weight parts of t-dodecyl mercaptan, and 0.1 weight parts of NaCl with respect to 85 weight parts of methyl methacrylate (MMA), 5 weight parts of benzyl methacrylate (BzMA), and 10 weight parts of methacrylic acid (MAA) was prepared.
The prepared mixture was primarily suspension-polymerized at an initial reaction temperature of 80° C. for two hours, and then, the temperature was raised to 95° C. to perform secondary polymerization on the resultant material for one hour. The resultant material was then cleansed and dried to fabricate MMA-BzMA-MAA beads.
The obtained beads were re-extruded twice through a co-rotating twin screw extruder at 270° C. to prepare a resin in a state of pellet, and at this time, the degree of vacuum (Torr) was 20. The composition of the final resin is shown in Table 1 below and the physical properties of the final resin are shown in Table 3 below.
After the fabricated pellet was dried, an extruded film having a thickness of 180 μm was fabricated by using an extruder including a T-die. The fabricated film was stretched in a mechanical direction (MD) so as to be double and then stretched biaxially in a transverse direction (TD) so as to be triple, thus fabricating a film having a thickness of 60 μm, and TAC and PVA were bonded to the film to fabricate a polarization plate. The physical properties of the film fabricated thusly are shown in Table 5 below.
Except that the number of extrusions was three, a resin was fabricated through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 1, the physical properties of the final resin are shown in Table 3, and the physical properties of the film are shown in Table 5.
Except that 82 weight parts of methyl methacrylate (MMA), 10 weight parts of benzyl methacrylate (BzMA), and 8 weight parts of methacrylic acid (MAA) were used, a resin was prepared through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 1, the physical properties of the final resin are shown in Table 3, and the physical properties of the film are shown in Table 5.
Except that 82 weight parts of methyl methacrylate (MMA), 10 weight parts of benzyl methacrylate (BzMA), and 8 weight parts of methacrylic acid (MAA) were used and that the number of extrusions was three, a resin was fabricated through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 1, the physical properties of the final resin are shown in Table 3, and the physical properties of the film are shown in Table 5.
Except that 77 weight parts of methyl methacrylate (MMA), 8 weight parts of benzyl methacrylate (BzMA), and 15 weight parts of methacrylic acid (MAA) were used and that first polymerization was performed at an initial reaction temperature of 90° C. and second polymerization was performed at the same temperature 90° C., without increasing the temperature, a resin was fabricated through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 1, the physical properties of the final resin are shown in Table 3, and the physical properties of the film are shown in Table 5.
Except that 82 weight parts of methyl methacrylate (MMA) and 8 weight parts of benzyl methacrylate (BzMA) were used, a resin was fabricated through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 1, the physical properties of the final resin are shown in Table 3, and the physical properties of the film are shown in Table 5.
Except that 78 weight parts of methyl methacrylate (MMA), 10 weight parts of benzyl methacrylate (BzMA), and weight parts of methacrylic acid (MAA) were used and that first polymerization was performed at an initial reaction temperature of 90° C., a resin was prepared through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 1, the physical properties of the final resin are shown in Table 3, and the physical properties of the film are shown in Table 5.
Except that 90 weight parts of methyl methacrylate (MMA), 0 weight parts of benzyl methacrylate (BzMA), and 10 weight parts of methacrylic acid (MAA) were used, a resin was prepared through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 2, the physical properties of the final resin are shown in Table 4, and the physical properties of the film are shown in Table 6.
Except that an extrusion process was not performed, a resin was fabricated through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 2, the physical properties of the final resin are shown in Table 4, and the physical properties of the film are shown in Table 6.
Except that extrusion was performed three times at an extrusion temperature of 200° C., a resin was fabricated through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 2, the physical properties of the final resin are shown in Table 4, and the physical properties of the film are shown in Table 6.
Except that extrusion was performed once at an extrusion temperature of 250° C., a resin was fabricated through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 2, the physical properties of the final resin are shown in Table 4, and the physical properties of the film are shown in Table 6.
Except that 78 weight parts of methyl methacrylate (MMA), 10 weight parts of benzyl methacrylate (BzMA), and weight parts of methacrylic acid (MAA) were used and that first polymerization was performed at an initial reaction temperature of 90° C. and second polymerization was performed at the same temperature 90° C. without increasing the temperature, and that an extrusion process was not performed, a resin was prepared through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 2, the physical properties of the final resin are shown in Table 4, and the physical properties of the film are shown in Table 6.
Except that 90 weight parts of methyl methacrylate (MMA), 10 weight parts of benzyl methacrylate (BzMA), and 0 weight parts of methacrylic acid (MAA) were used and that first polymerization was performed at an initial reaction temperature of 90° C. and second polymerization was performed at 95° C., and that an extrusion process was not performed, a resin was prepared through the same process as that of Embodiment 1. The composition of the final resin is shown in Table 2, the physical properties of the final resin are shown in Table 4, and the physical properties of the film are shown in Table 6.
The compositions of the final resins and physical evaluation method of the final resin were as follows.
1. Weight-average molecular weight (Mw): The prepared resin was dissolved in tetrahydropurane and measured by using gel permeation chromatography (GPC).
2. Tg (Glass transition temperature): Measured by using a Pyris 6 DSC from Perkin Elmer Inc.
3. Haze and light transmittance: Measured based on an ASTM 1003 method.
4. Composition of final resin: Measured by using C13-NMR.
| TABLE 1 | |||||||
| Final resin | Embodiment | Embodiment | Embodiment | Embodiment | Embodiment | Embodiment | Embodiment |
| composition | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| BzMA | 6 | 6.1 | 10.2 | 10.2 | 8.4 | 8.3 | 10.1 |
| MMA | 84.2 | 84.2 | 81.7 | 81.5 | 77.5 | 81.7 | 78.2 |
| MAA | 2.2 | 1.2 | 1.6 | 1.1 | 2.8 | 1.7 | 2.0 |
| G/A | 7.6 | 8.5 | 6.5 | 7.2 | 11.3 | 8.3 | 9.7 |
| * BzMA: Benzyl methacrylate | |||||||
| * MMA: Methyl methacrylate | |||||||
| * MAA: Methacrylic acid | |||||||
| * G/A: Glutaric anhydride | |||||||
| TABLE 2 | ||||||
| Final resin | Comparative | Comparative | Comparative | Comparative | Comparative | Comparative |
| composition | Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 |
| BzMA | 0 | 5.9 | 5.8 | 5.9 | 8.3 | 10.2 |
| MMA | 90.3 | 84.4 | 84.5 | 84.5 | 77.5 | 88.7 |
| MAA | 1.8 | 9.7 | 7.5 | 7.3 | 14.2 | 0 |
| G/A | 7.9 | 0 | 2.2 | 2.3 | 0 | 1.1 |
| TABLE 3 | |||||||
| Physical properties | Embodiment | Embodiment | Embodiment | Embodiment | Embodiment | Embodiment | Embodiment |
| of resin | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| Mw | 120000 | 118000 | 130000 | 129000 | 103000 | 122000 | 115000 |
| Tg (° C.) | 128 | 129 | 123 | 124 | 129 | 124 | 126 |
| Haze (%) | 0.2 | 0.2 | 0.1 | 0.2 | 0.3 | 0.2 | 0.2 |
| Light | 93.4 | 93.3 | 92.7 | 92.6 | 92.1 | 93.2 | 92.2 |
| transmittance (%) | |||||||
| TABLE 4 | ||||||
| Physical properties | Comparative | Comparative | Comparative | Comparative | Comparative | Comparative |
| of resin | Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 |
| Mw | 130000 | 122000 | 121000 | 12000 | 106000 | 123000 |
| Tg (° C.) | 130 | 124 | 125 | 125 | 125 | 103 |
| Haze (%) | 0.2 | 0.3 | 0.2 | 0.2 | 0.4 | 0.2 |
| Light | 93.3 | 93.1 | 93.1 | 92.9 | 91.3 | 92.1 |
| transmittance (%) | ||||||
A method for evaluating the physical properties of the film according to an embodiment of the present invention is as follows.
1. Retardation value (Rin, Rth): Measured by using an Elli-SE from Ellipso Tech. Co., Ltd.
2. Toughness: Measured by bending a 60 μm film ten times by hand to check whether or not it would break (⊚: unbroken, ∘: broken one to three times, x: broken five or more times)
3. CTE: Measured using a Perkin-Elmer TMA.
| TABLE 5 | |||||||
| Physical properties | Embodiment | Embodiment | Embodiment | Embodiment | Embodiment | Embodiment | Embodiment |
| of film | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| Rin/Rth | 0.3/−0.1 | 0.3/−0.2 | 0.7/−0.9 | 0.7/1.0 | 2.2/−2.5 | 1.6/−0.7 | 1.1/0.1 |
| Toughness | ⊚ | ⊚ | ⊚ | ⊚ | ◯ | ⊚ | ⊚ |
| CTE | 58 | 55 | 62 | 59 | 51 | 58 | 54 |
| (ppm/° C.) | |||||||
| TABLE 6 | ||||||
| Physical properties | Comparative | Comparative | Comparative | Comparative | Comparative | Comparative |
| of film | Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 |
| Rin/Rth | 10.9/13.1 | 0.4/0.2 | 0.3/0.1 | 0.3/0.1 | 2.0/−2.1 | 1.1/1.3 |
| Toughness | ◯ | ⊚ | ⊚ | ⊚ | ⊚ | ◯ |
| CTE | 57 | 82 | 78 | 76 | 77 | 81 |
| (ppm/° C.) | ||||||
As described above, it was confirmed that when the acrylic copolymer resin and film are fabricated by using the monomer content and process according to embodiments of the present invention, the coefficient of thermal expansion was drastically reduced, and in the case of Comparative Example 1, it was not within the retardation range available for use as a polarizer protective film, although it had a reduced CTE.
Namely, in the present invention, the CTE can be lowered while satisfying the basic conditions with respect to the polarizer protective film such as retardations by polymerizing using particular compositions and contents of monomers and performing a thermal treatment thereupon.
Claims (13)
1. A method for preparing an acrylic copolymer resin for an optical film, the method comprising:
suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare an acrylic copolymer; and
thermally treating the acrylic copolymer at a temperature ranging from 240° C. to 300° C.,
wherein the suspension-polymerizing comprises:
a first polymerization operation of performing suspension polymerization at an initial reaction temperature ranging from 60° C. to 90° C. for two to three hours; and
a second polymerization operation of increasing the temperature by 5° C. to 20° C., based on the temperature of the first polymerization operation, and additionally performing polymerization for one to two hours,
wherein the acrylic copolymer resin for an optical film obtained by the preparation method includes glutaric anhydride, and
wherein the acrylic copolymer resin for an optical film obtained through the preparation method includes 3 to 15 weight parts of an acrylic unit containing a benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate unit, 0 to 4 weight parts of a (meth)acrylic acid unit, and 5 to 16 weight parts of a glutaric anhydride unit, over 100 weight parts of the acrylic copolymer resin.
2. The method of claim 1 , wherein the second polymerization operation is performed at a temperature ranging from 80° C. to 100° C.
3. The method of claim 1 , wherein, in the preparing of the acrylic copolymer, 3 to 15 weight parts of an acrylic monomer containing a benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate monomer, and 5 to 20 weight parts of a (meth)acrylic acid monomer are suspension-polymerized.
4. The method of claim 1 , wherein, in the preparing of the acrylic copolymer, 3 to 15 weight parts of a benzylmethacrylate monomer, 65 to 92 weight parts of a methylmethacrylate monomer, and 5 to 20 weight parts of a methacrylic acid monomer are suspension-polymerized.
5. The method of claim 1 , wherein the acrylic monomer containing a benzene ring is selected from the group consisting of benzyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, 2-phenylethyl methacrylate, 3-phenylpropyl methacrylate, 3-phenylpropyl acrylate, and 2-phenoxyethyl acrylate.
6. The method of claim 1 , wherein the alkyl group of the alkyl(meth)acrylate monomer has 1 to 10 carbon atoms.
7. The method of claim 1 , wherein the alkyl(meth)acrylate monomer is selected from the group consisting of methylacrylate, ethylacrylate, methylmethacrylate, ethylmethacrylate, methylethacryate, and ethylethacrylate.
8. The method of claim 1 , wherein the (meth)acrylic acid monomer is selected from the group consisting of acrylic acid, methacrylic acid, methylacryl acid, methylmethacrylic acid, ethylacrylic acid, ethylmethacrylic acid, butylacrylic acid, and butylmethacrylic acid.
9. The method of claim 1 , wherein a glass transition temperature of the acrylic copolymer resin is 120° C. or higher.
10. The method of claim 1 , wherein haze of the acrylic copolymer resin ranges from 0.1 to 1%, and transmittance thereof is 90% or more.
11. The method of claim 1 , wherein the thermal treatment is performed as an extrusion operation.
12. The method of claim 11 , wherein the extrusion operation is performed by performing a re-extrusion two to five times by using a twin screw extruder.
13. The method of claim 11 , wherein the extrusion operation is performed in vacuum at a pressure lower than 40 torr.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR20110034443 | 2011-04-13 | ||
| KR10-2011-0034443 | 2011-04-13 | ||
| KR10-2011-0083999 | 2011-08-23 | ||
| KR1020110083999A KR101270220B1 (en) | 2011-04-13 | 2011-08-23 | Method for producing acryl-based copolymer for optical film and method for producing optical film using the same |
| PCT/KR2012/000869 WO2012141422A1 (en) | 2011-04-13 | 2012-02-07 | Method for preparing acrylic copolymer resin for optical film and method for fabricating optical film using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| US20140015152A1 US20140015152A1 (en) | 2014-01-16 |
| US9429682B2 true US9429682B2 (en) | 2016-08-30 |
Family
ID=47285022
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US14/006,267 Active 2033-02-20 US9429682B2 (en) | 2011-04-13 | 2012-02-07 | Method for preparing acrylic copolymer resin for optical film and method for fabricating optical film using the same |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US9429682B2 (en) |
| JP (1) | JP5796837B2 (en) |
| KR (2) | KR101270220B1 (en) |
| TW (1) | TWI491621B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11815658B2 (en) | 2017-02-20 | 2023-11-14 | Trinseo Europe Gmbh | Transparent films based on resin components having a high glass transition temperature |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101347021B1 (en) | 2011-06-01 | 2014-01-07 | 주식회사 엘지화학 | Resin compositions and optical films formed by using the same |
| US9767986B2 (en) | 2014-08-29 | 2017-09-19 | Kla-Tencor Corporation | Scanning electron microscope and methods of inspecting and reviewing samples |
| KR101717442B1 (en) * | 2015-01-23 | 2017-03-17 | 엘지엠엠에이 주식회사 | Cross-linked methacrylate copolymer for polycarbonate, polycarbonate composition |
| CN107849189B (en) * | 2015-07-31 | 2021-04-13 | 三菱化学株式会社 | Copolymer, method for producing copolymer, resin composition, molded body, and vehicle |
| US10431441B2 (en) * | 2018-01-31 | 2019-10-01 | Palodex Group Oy | Reducing calibration of components in an imaging plate scanner |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61254608A (en) | 1985-05-02 | 1986-11-12 | Sumitomo Chem Co Ltd | Production of thermoplastic copolymer having improved heat deformation resistance |
| US4789709A (en) | 1985-05-02 | 1988-12-06 | Sumitomo Chemical Company, Limited | Process for the production of heat resistant thermoplastic copolymer |
| US4874824A (en) | 1987-11-23 | 1989-10-17 | Rohm And Haas Company | Process for manufacturing low-acid, glutaric-anhydride-containing copolymers |
| JP2008101202A (en) | 2006-09-21 | 2008-05-01 | Toray Ind Inc | Acrylic film |
| JP2009227720A (en) | 2008-03-19 | 2009-10-08 | Toray Ind Inc | Method for producing thermoplastic copolymer |
| US20090275718A1 (en) | 2008-04-30 | 2009-11-05 | Lg Chem, Ltd. | Resin composition and optical films formed by using the same |
| JP2009292869A (en) | 2008-06-02 | 2009-12-17 | Fujifilm Corp | Acrylic film, method for producing it, polarizing plate, optical compensation film, antireflection film, and liquid crystal display |
| WO2010013557A1 (en) | 2008-07-31 | 2010-02-04 | 旭化成ケミカルズ株式会社 | Thermoplastic acrylic resin, and molded product thereof |
| KR20100097183A (en) | 2007-12-27 | 2010-09-02 | 아사히 가세이 케미칼즈 가부시키가이샤 | Thermoplastic acrylic resin and molded body for optical member |
| KR20100104518A (en) | 2009-03-18 | 2010-09-29 | 주식회사 엘지화학 | Acryl-based copolymer, optical film and liquid crystal display comprising the same |
| JP2011511101A (en) | 2008-01-08 | 2011-04-07 | エルジー・ケム・リミテッド | Transparent resin composition |
-
2011
- 2011-08-23 KR KR1020110083999A patent/KR101270220B1/en active Active
-
2012
- 2012-02-07 JP JP2013544407A patent/JP5796837B2/en active Active
- 2012-02-07 US US14/006,267 patent/US9429682B2/en active Active
- 2012-04-10 TW TW101112624A patent/TWI491621B/en active
-
2013
- 2013-01-04 KR KR1020130001150A patent/KR101335618B1/en active Active
Patent Citations (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61254608A (en) | 1985-05-02 | 1986-11-12 | Sumitomo Chem Co Ltd | Production of thermoplastic copolymer having improved heat deformation resistance |
| EP0264508A1 (en) | 1985-05-02 | 1988-04-27 | Sumitomo Chemical Company, Limited | Process for the production of heat resistant thermoplastic copolymer |
| US4789709A (en) | 1985-05-02 | 1988-12-06 | Sumitomo Chemical Company, Limited | Process for the production of heat resistant thermoplastic copolymer |
| US4874824A (en) | 1987-11-23 | 1989-10-17 | Rohm And Haas Company | Process for manufacturing low-acid, glutaric-anhydride-containing copolymers |
| JP2008101202A (en) | 2006-09-21 | 2008-05-01 | Toray Ind Inc | Acrylic film |
| KR20100097183A (en) | 2007-12-27 | 2010-09-02 | 아사히 가세이 케미칼즈 가부시키가이샤 | Thermoplastic acrylic resin and molded body for optical member |
| US20110009585A1 (en) | 2007-12-27 | 2011-01-13 | Masami Yonemura | Thermoplastic acrylic resin and molded body for optical member |
| JP2011511101A (en) | 2008-01-08 | 2011-04-07 | エルジー・ケム・リミテッド | Transparent resin composition |
| JP2009227720A (en) | 2008-03-19 | 2009-10-08 | Toray Ind Inc | Method for producing thermoplastic copolymer |
| US20090275718A1 (en) | 2008-04-30 | 2009-11-05 | Lg Chem, Ltd. | Resin composition and optical films formed by using the same |
| JP2009292869A (en) | 2008-06-02 | 2009-12-17 | Fujifilm Corp | Acrylic film, method for producing it, polarizing plate, optical compensation film, antireflection film, and liquid crystal display |
| WO2010013557A1 (en) | 2008-07-31 | 2010-02-04 | 旭化成ケミカルズ株式会社 | Thermoplastic acrylic resin, and molded product thereof |
| US20110130535A1 (en) | 2008-07-31 | 2011-06-02 | Masami Yonemura | Thermoplastic Acrylic Resin, and Molded Product Thereof |
| KR20100104518A (en) | 2009-03-18 | 2010-09-29 | 주식회사 엘지화학 | Acryl-based copolymer, optical film and liquid crystal display comprising the same |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11815658B2 (en) | 2017-02-20 | 2023-11-14 | Trinseo Europe Gmbh | Transparent films based on resin components having a high glass transition temperature |
Also Published As
| Publication number | Publication date |
|---|---|
| JP5796837B2 (en) | 2015-10-21 |
| KR20120116840A (en) | 2012-10-23 |
| KR101335618B1 (en) | 2013-12-02 |
| KR20130018967A (en) | 2013-02-25 |
| KR101270220B1 (en) | 2013-05-30 |
| JP2014501293A (en) | 2014-01-20 |
| CN103443147A (en) | 2013-12-11 |
| TWI491621B (en) | 2015-07-11 |
| TW201245236A (en) | 2012-11-16 |
| US20140015152A1 (en) | 2014-01-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101269673B1 (en) | Resin composition for optical film and optical film using the same | |
| JP5928852B2 (en) | Method for producing resin composition for optical film by continuous bulk polymerization method, method for producing optical film and polarizing plate using the same | |
| US9429682B2 (en) | Method for preparing acrylic copolymer resin for optical film and method for fabricating optical film using the same | |
| CN102933624B (en) | Acrylic copolymer having high heat resistance and high strength and optical film comprising same | |
| CN105829923B (en) | Optical thermoplastic resin and molded body | |
| JP2006337493A (en) | Polarizer protective film, method for producing the same, and polarizing plate using the same | |
| JP5965621B2 (en) | Optical film and manufacturing method thereof | |
| JP2010054750A (en) | Method for manufacturing retardation film | |
| JP5804298B2 (en) | Acrylic copolymer and resin composition containing the same | |
| JP5433328B2 (en) | Retardation film | |
| KR20120055061A (en) | Methacrylic copolymer and phase difference film comprising the same | |
| JP5965612B2 (en) | Optical film and manufacturing method thereof | |
| JP7779856B2 (en) | Glutarimide Resin | |
| JP2012068430A (en) | Retardation film | |
| KR101497180B1 (en) | Acryl copolymer having excellent strength, resin composition comprising the same, opticla film and ips mode liquid crystal display comprising thereof | |
| CN103443147B (en) | Prepare the method for blooming acrylic copolymer resin and use its method manufacturing blooming | |
| KR101304589B1 (en) | Composition for optical film having excellent transparency, strength and heat resistance and optical film comprising the same | |
| WO2012141422A1 (en) | Method for preparing acrylic copolymer resin for optical film and method for fabricating optical film using the same | |
| KR101110607B1 (en) | Retardation film | |
| KR101565629B1 (en) | Resin composition for optical film and optical film using the same | |
| JP2009047950A (en) | Optical compensation film |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| AS | Assignment |
Owner name: LG CHEM, LTD., KOREA, REPUBLIC OF Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CHOI, EUN-JUNG;HAN, CHANG-HUN;SEO, JAE-BUM;AND OTHERS;REEL/FRAME:031243/0624 Effective date: 20130213 |
|
| FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
| STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
| MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 4 |
|
| MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 8TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1552); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 8 |